Anthem, as it did with its Ohio pullout, blamed a "volatile" market for individual health plans, as well as "uncertainty" about the federal government's stance on Obamacare's rules and regulations.

The insurer also said it was worried about whether the Trump administration will continue paying insurers billions of dollars in reimbursements for subsidies that reduce out-of-pocket health costs to low-income Obamacare customers.

Anthem said Wednesday it will offer just one individual health plan outside of the HealthCare.gov Obamacare marketplace in a single county in Wisconsin, and one such plan also sold outside of that federally run marketplace in five Indiana counties.

By offering those plans, Anthem will avoid a five-year ban on re-entering the individual health plan markets that is imposed on insurers who completely exit a state's Obamacare market.

Anthem currently sells Obamacare plans in 14 states. So far, it has announced plans to almost completely pull out of three of those states in 2018, and it is not clear how many states Anthem may depart.

"After significant dialogue with state leaders and regulators Anthem has made the difficult decision to reduce its 2018 Individual plan offerings in Wisconsin and Indiana," the insurer said.

"While we are pleased that some steps have been taken to address the long-term challenges all health plans serving the Individual market are facing, the Individual market remains volatile," Anthem said.

"Today, planning and pricing for ACA-compliant health plans has become increasingly difficult due to a shrinking and deteriorating individual market, as well as continual changes and uncertainty in federal operations, rules and guidance, including cost-sharing reduction subsidies and the restoration of taxes on fully insured coverage."

Anthem's decision Wednesday does not affect the company's business selling employer-based health coverage, Medicare Advantage, or Medicaid plans in Wisconsin or Indiana.

"We will continue to advocate solutions that will stabilize the market and allow us return to a more robust presence in the future," Anthem said.

"In those states where Anthem has not yet made a final participation decision, we continue to work with regulators and remain actively engaged in dialogue."

Larry Levitt, an Obamacare expert at the Kaiser Family Foundation, said: "There is no question that Anthem has soured on the marketplace, given underlying instability and the tremendous uncertainty stoked by the Trump administration and the health-care debate in Congress."

"Assuming other insurers in Indiana and Wisconsin stick around, there will still be at least one insurer in all counties in these states," Levitt said.